How to set Textbody value with Python-Script (Adding a text and editing the body)?
This is how I solved it:

import bpy
import bmesh

def create():
    scn = bpy.context.scene
    scn.render.engine = 'CYCLES'
    scn.world.use_nodes = True
    set_background()    
#context
    bpyscene = bpy.context.scene

# Create an empty mesh and the object.
    mesh = bpy.data.meshes.new('Basic_Sphere')
    basic_sphere = bpy.data.objects.new("Basic_Sphere", mesh)

# Add the object into the scene.
    bpyscene.objects.link(basic_sphere)
    bpyscene.objects.active = basic_sphere
    basic_sphere.select = True

# Construct the bmesh cube and assign it to the blender mesh.
    bm = bmesh.new()
    bmesh.ops.create_uvsphere(bm, u_segments=32, v_segments=16, diameter=1)
    bm.to_mesh(mesh)
    bm.free()

# add subsurf mod and smooth
    bpy.ops.object.modifier_add(type='SUBSURF')
    bpy.ops.object.shade_smooth()
# add material to the UV Sphere
    ob = bpy.context.active_object
    ob.select = True
#scene.objects.active = ob

# Get material
    g_mat = bpy.data.materials.get("green_glow")
    if g_mat is None:
    # create material
        create_materials("green_glow")        
    g_mat = bpy.data.materials.get("green_glow")
# Assign it to object
    if ob.data.materials:
    # assign to 1st material slot
        ob.data.materials[0] = g_mat        
    else:
    # no slots
        ob.data.materials.append(g_mat)
    print ("Green Material assigned")

# move UV Sphere
    bpy.ops.object.move_to_layer(layers=(False, False, False, False, False, False, False, False, False, False, True, False, False, False, False, False, False, False, False, False))

# Text
bpy.ops.object.text_add(view_align=False, enter_editmode=False, location=(0, 0, 0), layers=(True, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False))
bpy.ops.transform.rotate(value=1.5708, axis=(1, 0, 0), constraint_axis=(True, False, False), constraint_orientation='GLOBAL', mirror=False, proportional='DISABLED', proportional_edit_falloff='SMOOTH', proportional_size=1)
bpy.context.object.data.extrude = 0.02
# Delete default "Text"
bpy.ops.object.editmode_toggle()
bpy.ops.font.delete(type='PREVIOUS_OR_SELECTION')
bpy.ops.font.delete(type='PREVIOUS_OR_SELECTION')
bpy.ops.font.delete(type='PREVIOUS_OR_SELECTION')
bpy.ops.font.delete(type='PREVIOUS_OR_SELECTION')
bpy.ops.font.delete(type='PREVIOUS_OR_SELECTION')
# Set new word
chars = "Digital"
for char in chars:
    bpy.ops.font.text_insert(text=char)
bpy.ops.object.editmode_toggle()
# add material to the Text
ob.select = True
ob = bpy.context.active_object
#scene.objects.active = ob

# Get material
mat = bpy.data.materials.get("white_glow")
if mat is None:
    # create material
    create_materials("white_glow")
mat = bpy.data.materials.get("white_glow")
# Assign it to object
if ob.data.materials:
    # assign to 1st material slot
    ob.data.materials[0] = mat
else:
    # no slots
    ob.data.materials.append(mat)
print ("Green Material assigned")
# text to mesh
bpy.ops.object.convert(target='MESH')
# Particle system
bpy.ops.object.particle_system_add()
bpy.data.particles["ParticleSettings"].effector_weights.gravity = 0
bpy.data.particles["ParticleSettings"].render_type = 'OBJECT'
bpy.data.particles["ParticleSettings"].dupli_object = 
bpy.data.objects["Basic_Sphere"]

def set_background():
# darken the background   
bpy.context.scene.world.node_tree.nodes['Background']
.inputs['Color'].default_value = (0, 0, 0, 1)

print("Set background color")

def create_materials(mat_name):
mat = bpy.data.materials.new(name=mat_name)
# get the material
mat = bpy.data.materials[mat_name]
mat.use_nodes = True
# get the nodes
nodes = mat.node_tree.nodes

# clear all nodes to start clean
for node in nodes:
    nodes.remove(node)

# create emission node
node_emission = nodes.new(type='ShaderNodeEmission')
if (mat_name == "white_glow"):
    node_emission.inputs[0].default_value = (1,1,1,1)  # white RGBA
else:
    node_emission.inputs[0].default_value = (0,1,0,1)  # white RGBA
node_emission.inputs[1].default_value = 2.0 # strength
node_emission.location = 0,0

# create output node
node_output = nodes.new(type='ShaderNodeOutputMaterial')   
node_output.location = 400,0

# link nodes
links = mat.node_tree.links
link = links.new(node_emission.outputs[0], node_output.inputs[0])

# remove links
#links.remove(link)


# Animate Particle System
#def animate():

# Move / Animate Sphere

if __name__ == "__main__":
create()